Working furnaces by compressed air



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WORKING FURNACES BY COMPRESSED AIR.

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, WORKING FURNACES B-Y COMPRESSED IR. No. 352,423. Patented Nov; 9,1.886.

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WORKING FURNACES BY COMPRESSED AIR.

No. 352,423. Patented Nov. 9, 1886.

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' present in these gases the remaining heat and 7 UNITED STATES PATENT@rrrcn.

- CARL OTTO, GREIFENHAGEN, PRUSSIA, GERMANY.

WORKING FURNACES BY COMPRESSED AIR.

EPECIE'ICATION forming part of Letters Patent No. 352,423, datedNovember 9, 1886.

- Application filed August 14, 1886.

To all whom it may concern.-

Be it known that I, CARL OTTO, asubject of the King of Prussia, andresiding at Greifenhagen, Kingdom of Prussia,Germany, have invented newand useful Improvements in Working Furnaces by Means of Compressed Air,of which the following is a specification.

My invention relates to closed furnaces in which combustion ismaintained by compressed air; andthe objectof the same is to utilize thecompressed combustion'gases thus obtained, in the first place for thegeneration of steam or, in addition thereto, for other technicalpurposes, and in the second place for producing the mechanical work or apart thereof required to compress the air to be supplied to the furnace.

To this end my invention consists in the combination, with a closedfurnace, of a steamboiler receiving heat from the former, a pump forsupplying compressed air to the furnace, a hot-air engine worked by thecompressed combustion-gases from the said furnace, and a motorco-operating'with the hot-air engine in driving the air-pump.

The invention also comprises means for purifying the combustion-gases ontheir course from the furnace to the hot-air engine and mixing them withsteam, and means for feeding the furnace with solid fuel. If any fuel isburned in a closed space under pressure, the temperature, as well as thequantity of heat developed ,increases considerably, and thecombustion-gases produced are capable of exercising a greater calorificeffect on a given surfacefor instance, on the heating-surface of asteam-boileron account of their superior calorific capacity, (relativelyto the unit of volume,) originating from their greater density. Onissuing from the space or apparatus in which they have first given offheat there is still the whole mechanical energy resulting from theirexpansive force, which are both lost if the gases are allowed to escapeinto the atmosphere, so that under these conditions an economicaladvantage does not arise from the use of compressed air. A utilizationof the said heat and mechanical energy may, however, be attained bycausing the issuing combustion-gases to operate expansively in a hot-airengine, and

in employing the mechanical work thus pro- Serial No. 210,936. (Nomodel.)

duced for working the pump which supplies the compressed air requiredfor sustaining the combustion. 5 5

On the annexed three sheets of drawings an apparatus involving myinvention is represented by Figure 1 in a vertical sectional elevation,and by Fig. 2 in plan, partly in section. Fig. 3 shows the fuel-feederto a larger scale. Fig. 4 is a part in detail. Fig. 5 is a section ofthe air-pump, and Fig. .6 represents a portion of a modified apparatuswith furnace adapted for melting metals.

In Figs. 1 and 2, A is a'steam-boiler provided with the inside furnace,B. O is a fuel-feeder adapted for introducing fuel into the furnace Bwhile being under pressure. D is an apparatus in which thecombustiongases issuing from the said furnace are purified, and in 7which, if their temperature should be too high, they are cooled down tothe proper degree and impregnated with steam. E is the hot-air-engine;F, a steam-engine coupled with the former; G, the air-pump; H, anair-vessel inserted between the latter and the furnace, and in whichseparates out any water introduced into the air-pump for the purpose ofrefrigeration; and J, a water-reservoir, from which the waterevaporating in the purifier D is replaced.

The boiler A is represented as a vertical cylindrical boiler with Fieldtubes. In the lower. part of this boiler is formed, by means of afire-proof lining, a shaft, 12, into which air is 8 introduced below thegrate arranged therein through the pipe (1, the branch pipe at, and theapertures a, while through the branch at of the pipe a and the nozzlesto air is conveyed to the upper contracted portion orneck, b. A 0gas-furnace with generator is thus constituted, in which the maincombustion takes place in Y and immediately above the neck b. Forheating the air supporting the combustion, the pipes at and a are formedin scrpentines and 9 5 embedded in the fire-proof lining. A cockinserted between the pipe a and the pipes a. a serves for the regulationof the admission of air to the latter, while the combustion at b may beso regulated by a fire-proof cone, e, adjustable by the lever f and rodf, that a clear flame will be produced, even with the least possibleadmission of air.

The mixture of the air entering at a with the-gas, and consequently theintensity of combustion, may be promoted by a platinum disk, e, fixedupon the cone'eby apin of like metal. In order to allow the flame to beobserved, a small window, consisting of a pane of mica, is arranged at11*. i is a cock for blowing off ashes.

The furnace is first supplied with fuel and the fire kindled through theaperture 0. During the working this aperture remains closed, the fuelbeing then introduced by means of the contrivance C, or fuel-feeder,consisting in a cylinder, 01, with piston d, movable by hand, the hopperd", communicating with the said cylinder and adapted to be closedagainst the inside pressure by the cover d, and the piston-like valve dfitted with screw and handwheel; When the said valve is in closed state,the hopper may be opened and filled with fuel. The hopper having thenbeen reclosed by the cover (1 and the piston d drawn back, the valve israised, so that the contents .of the hop- .per will drop into thecylinder d, and thereupon screwed down again. The fuel may then bepushed by the piston from the cylinder into the channel 0, so thatfinally it will be conveyed into the furnace. This operation does notrequire any considerable force, provided the piston fits loosely enoughto allow the gas-pressure to act on both surfaces-of the same; also, theclosing of the valve (1 does not present any difficulty, as when thevalve is rotion between the boiler and the cylinder of the.

steam-engineF through the pipej, and thereby starting the same. The saidengine then puts in motion the air-pump G, connected thereto, so thatcompressed air will be forced through the pipe is into the air-vessel H,and thence through the pipes at, a, and a into the furnace.

At the same time the pipe at is closed by the valve m, the compressedcombustion-gases, after having given ofl the greater portion of theirheat to the boiler for the generation of steam, being thereby compelledto pass through the apparatus D (to be described hereinafter) to thecylinder of the hot-air engine E, where they are utilized expansively toassist the steam-engine in its operation.

Theoretically the hot-air engine should do .more work than the air-pumpabsorbs; but on account of the inevitable losses caused by leakage andradiation, the mechanical effect of the hot-air engine is ordinarilysomewhat inferior to the power required for driving thepump, and thisdeficiency must be compensated by the steam-engine or by any othermotor. The remaining power of the steam-engine may be utilized for otherpurposes.

The aforesaid apparatus D is but conditionally a necessary appurtenance.If the combustion-gases passing ofi from the boiler are sufficientlypure, and if they are not of too high temperature to be introduceddirectly into the hot-air'engine, the said apparatus may be dispensedwith; but usually, if min: eral coal is employed as fuel, the gasescontain ashes, vapors of tar, and sulphurous acid, which would injureand clog the engine. Besides, the temperature of the gasesis not to becontrolled sufficiently by the regulation of the combustion. In order toseparate out the said noxious admixtures and to prevent the temperaturefrom exceeding a certain limit, the gases are conducted through a Wateryalkaline solution contained in the vessel D, and which, on one hand,retains the sulphurous acid, the tarry vapors, and the ashes, while onthe other hand it takes up the surplus of free heat of the gases withgeneration of steam. If, for instance, the temperature of the gasesentering into D is 200 centigrade, and that of the liquid,which is underpressure,150,the quantity of heat corresponding to the difference of 50will become latent in the steam produced. Upon the expansion of thegases in the cylin der of the hot-air engine, and the decrease oftemperature resulting therefrom, the steam will be condensed,and itslatent heat, in becoming free again, will be. given back to the gases.In order to cause the gases to pass through the said liquid in thinstreams, the vessel D is provided with the bafile-plates 9, havingnotches at their lower edge, with which they dip into the liquid. (SeeFig. 4.) The inclined plates h have the purpose of separating out fromthe gascurrent any liquid carried along by the same, and to return it tothe vessel D. The water evaporated'in D is replaced, either at intervalsor continuously, from the reservoir J, which is connected by the pipe 0with the air-vessel H, in order to produce therein the same pressureasin D.

The water runs from J into D over the inclined plates It. For preventingor diminishing radiation of heat, the apparatus D, the gas-pipesconnected therewith, and the-hotair cylinder are surrounded by a jacket,p, through which the exhaust-steamfrom the steam-engine is conducted tothe pipe q, opening out into the pipe m.

For the purpose of reducing the power required for the compression ofthe air, the air- I drawings, and in the water-pipe y, opening out withits ends, which are also contracted at a right angle and close to theends of the pipe 9:. Two spray apparatuses are thus formed, which areactuated alternately by the air which is being compressed. Thisarrangement, however, does not form any part of my invention. The waterthus mixed with the air separates out again in theair-vessel H, whenceit is blown off at intervals.

The cylinders of the air-pump and of the hot-air engine are preferablymade of the same size, and the expansion-gear of the latter is soadjusted that the gases will expand to about atmospheric pressure. Thisdegree of expansion is admissible, because the frictional resistances ofthe said engine are overcome by the steam-engine, which in its turnprofits by the economization of heat by means of the joint arrangement.Considering that during each stroke the resistance in the air-pu mpincreases, while the pressure in the hotair engine decreases, it isadvantageous to so connect the respective pistons that the piston of thehotair engine begins its stroke under full pressure somewhat before themaximum pressure has been attained in the pump. The work produced in theformer and that consumed in the latter will, under these conditions,nearly balance each other in the different portions of the stroke.drawings, and in which the air-pump is actuated directly by the pistonrod of the steamengine, this relation between the said pistons isattained by placing the crank r of the steamengine at the requisiteobtuse angle to the crank s of the hot-air engine.

The heat developed in the furnace may be utilized for other purposesbesides that of generating steamfor instance, for melting metals. Anapparatus adapted for this purpose isrepresented by Fig. 6. The gasgenerator I), provided with fuel-magazineshaft t,'is placed below themelting-furnace u with hearth u.

The gas produced in b is conducted by the channel 2) to the apertures'v, and the air from the pipe a to the apertures a. The combustion-gasespass through the channels to and w into a steam-boiler. The shaftz isdesigned for the reception of a mold, 2, into which the liquid metal maybe run under pressurein view of producing castings that are free frompores.

1 claim as my invention 1. The combination,with a closed furnace,of asteam-boiler receiving heatfrom the former,

In the arrangement shownby the a pump for supplying compressed air tothe furnace, a hot-air engine worked by the compressed combustion-gasesfrom the said furnace, and a motor co-operating with the hotair enginein driving the air-pump, substantially as and for the purpose described.

2. The combination, with a steam-boiler, A, of a closed furnace, B, anair-pum p, G, supplying compressed air to the furnace through the pipesat and c the hot-air engine E, worked by the compressed combustion-gasesfrom the furnace, and a steam-engine, F, connected to the boiler A andcoupled with the engine E, the said engines E and F driving the air-pumpG, substantially as and for the purpose specified.

3. The combination,with a closed furnace, a steam-boiler, a pumpsupplying compressed air to the furnace, a hot-air engine connected tothe furnace, and a motor co-operating with the hot-air engine in drivingthe air-pump, of means for purifying the compressed combustion-gases ontheir course from the furnace to the hot-air engine, for reducing theirtemperature and for mixing them with steam, substantially ashereinbefore set forth.

4. The combination, with the closed furnace B, steam-boiler A,air-compressing pump G, hot-air engine E,connected to thefurnace, andsteam-engine F, connected to the boiler and coupled with the engine E,of the gas-purifier D, containing a watery alkaline solution andprovided with the baffle-plates g, substantially as described.

5. The combination, with the closed furnace B, in which combustion iskept up under pressure, of the fuel-feeder 0, comprising the cylinder(Z, piston d, hopper 01*, with cover d, and valve (1 provided with meansfor operating it and keeping it closed against the pressure actingthereon, substantially as and for the purpose specified.

6. The combination, with asteam-boiler, A, the air-compressing pump G,the hot-air engine E, and the steam-engine F, of a furnace adapted formelting metals, substantially as set forth.

In testimony whereof I have hereunto set my hand in the presence of twosubscribing wit-

